JP2014194954A - Led-base pedestal type lighting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lamp and an electric bulb of solid light source which are constituted so as to provide a desired light emission pattern, have efficient and highly reliable heat management characteristics and have high cost-effectiveness.SOLUTION: An LED lamp 120 includes a slender pedestal 122 having a plurality of surfaces. A plurality of solid light sources 124 are included, each of the solid light sources 124 can be attached to one of the surfaces, and the pedestal 122 includes a heat conductive path for conducting heat so as to be separated from the solid light source 124. A diffuser dome 130 is constituted for the solid light source 124, light from the solid light source 124 passes through the diffuser dome 130 and the diffuser dome 130 modifies an emission pattern of the solid light source 124 to generate a desired electric bulb radiation pattern.

Description

  This application claims the benefit of US Provisional Patent Application No. 61 / 339,516, filed March 3, 2010, and US Provisional Patent Application No. 61 / 339,515, filed March 3, 2010.

  The present invention relates to solid state lamps and bulbs, and in particular to light emitting diode (LED) based lamps and bulbs that can provide an omnidirectional emission pattern similar to that of filament-based light sources.

  Light emitting diodes (LEDs) are solid state devices that convert electrical energy into light and typically include one or more active semiconductor material layers sandwiched between oppositely doped layers. When a bias is applied across the doped layer, holes and electrons are injected into the active layer, and the holes and electrons recombine within the active layer to generate light. Light is emitted from the active layer and all surfaces of the LED.

  To use an LED chip within a circuit or other similar configuration, the LED chip may be sealed in a package to provide environmental and / or mechanical protection, color selection, light collection, and the like. Are known. The LED package also includes electrical leads, contacts, or traces that electrically connect the LED package to external circuitry. In the exemplary LED package 10 shown in FIG. 1, a single LED chip 12 is mounted on a reflective cup 13 by soldering or conductive epoxy. One or more wire bonds 11 connect the ohmic contacts of the LED chip 12 to the leads 15A and / or 15B, and the leads 15A and / or 15B can be attached to the reflective cup 13 or Can be integrated. The reflective cup can be filled with an encapsulant 16 that can contain a wavelength converting material such as a phosphor. The light emitted by the LED at the first wavelength can be absorbed by the phosphor, and the phosphor can emit light at the second wavelength accordingly. The entire assembly is then encapsulated in a transparent protective resin 14, which can be molded into the shape of a lens so that the light emitted from the LED chip 12 is parallel. The reflection cup 13 can guide light upward, but light loss may occur when the light is reflected (that is, some of the actual reflector surface reflectance is less than 100%, Light may be absorbed by the reflector cup). Furthermore, since it may be difficult to remove heat through the leads 15A, 15B, heat retention may be a problem for packages such as the package 10 shown in FIG.

  The conventional LED package 20 shown in FIG. 2 may be more suitable for high power operation that can generate more heat. Within the LED package 20, one or more LED chips 22 are mounted on a carrier, such as a printed circuit board (PCB) carrier, a substrate, or a submount 23. A metal reflector 24 mounted on the submount 23 surrounds the LED chip (s) 22 and reflects the light emitted by the LED chip 22 away from the package 20. The reflector 24 also provides mechanical protection for the LED chip 22. Between the ohmic contact on the LED chip 22 and the electrical traces 25A, 25B on the submount 23, one or more wire bond connections 11 are formed. Next, the attached LED chip 22 is covered with a capsule 26. Capsule 26 can also act as a lens while providing environmental and mechanical protection to the chip. Metal reflector 24 is typically attached to the carrier by solder or epoxy bonds.

  LED chips, such as those found in the LED package 20 of FIG. 2, can be coated with a conversion material that includes one or more phosphors, which phosphors absorb at least a portion of the LED light. LED chips can emit light of different wavelengths and thus emit a combination of light from the LED and light from the phosphor. The LED chip (s) can be coated with the phosphor using a number of different methods, and one suitable method is called the “Whifer Level Phosphorating Method and Devices Fabricated Customizing Method”, both by Chitnis et al. No. 11 / 656,759 and 11 / 899,790 in the name of the application. Alternatively, these LEDs can be coated using other methods, such as electrophoretic deposition (EPD), and a suitable EPD method is named Tarsa et al., “Close Loop Electrodeposition of Semiconductor Devices” U.S. Patent Application No. 11 / 473,089.

  In these examples, the phosphor material is located on or in close proximity to the LED epitaxial layer and optionally includes an insulating protective coating over the LED. In these configurations, the phosphor material can be directly subjected to the heat of the chip, thereby heating the phosphor material. Such an increase in operating temperature can cause deterioration of the phosphor material over time. Moreover, there is a possibility that the conversion efficiency of the phosphor is reduced and the conversion color is changed.

  Lamps have been developed that utilize a solid state light source such as an LED and where the conversion material is separated from the LED or spaced apart from the LED. Such an arrangement is disclosed in US Pat. No. 6,350,041, entitled “High Output Radial Dispersing Lamp Using a Solid State Light Source” by Tarsa et al. The lamp described in this patent can include a solid state light source that transmits light through a separator to a disperser having a phosphor. The disperser can disperse the light in a desired pattern and / or change the color of the light by converting at least a portion of the light by the phosphor. In some embodiments, the separator sufficiently separates the light source from the disperser so that heat from the light source is not transferred to the disperser when the light source is carrying the high current required for room lighting.

  In order to achieve wide-angle illumination, LED-based bulbs have been developed that utilize a number of low-intensity LEDs (eg, 5 mm LEDs) mounted on a three-dimensional surface. However, these designs do not provide an optimized omnidirectional emission that falls within standard uniformity requirements. These bulbs also include a large number of interconnected LEDs, which makes them very complex, expensive and unreliable. As such, these LED bulbs are usually impractical for most lighting purposes.

  Other LED bulbs have also been developed that use a mesa-type design as the light source, with one LED on the top surface and seven more LEDs on the mesa sidewall (GeoBulb® provided by C. Crane). ) -II). However, this configuration provides a substantially forward biased pattern rather than an omnidirectional emission pattern. This bulb mesa also includes a hollow shell, which may limit the ability to thermally dissipate heat from the radiant section. This can limit the drive current that can be applied to the LED. This design is also relatively complex, uses several LEDs and is not suitable for mass production of low cost LED bulbs.

US patent application Ser. No. 11 / 656,759 US patent application Ser. No. 11 / 899,790 US patent application Ser. No. 11 / 473,089 US Pat. No. 6,350,041

  The present invention provides various embodiments of efficient, reliable and cost-effective lamps and bulbs that can be configured to provide an omnidirectional emission pattern. In another embodiment, a solid radiating section configured on the pedestal can be included and has a thermal management feature to control heat accumulation in the radiating section. These embodiments can also include molded spaced phosphors and can also have thermal management features to control the conversion heat conversion within the spaced phosphors. Different embodiments can also have diffuser features to produce the desired emission pattern for lamps and bulbs.

  One embodiment of a lamp according to the invention comprises a pedestal and a solid state light source on the pedestal. A shaped phosphor spaced apart from the solid state light source is constructed so that at least some light from the solid state light source passes through the spaced phosphor and is converted to light of a different wavelength. A diffuser is included to diffuse the light emitted from the lamp in an omnidirectional emission pattern.

  One embodiment of an LED-based bulb according to the present invention comprises an elongated pedestal having a plurality of surfaces. Multiple LEDs are included, each of which can be attached to one of the surfaces, and the pedestal includes a thermally conductive path for conducting heat away from the LEDs. A diffuser is configured for the LED so that the light from the LED passes through the diffuser, which modifies the emission pattern of the LED to produce the desired bulb emission pattern.

  Another embodiment of a solid state lamp according to the invention comprises a pedestal having a plurality of solid state light sources, the pedestal comprising at least part of a thermally conductive material. A heat sink structure is included and the pedestal is thermally coupled to the heat sink structure. Heat from the solid state light source is transferred to the heat sink structure through the pedestal. A spaced phosphor that is thermally coupled to the heat sink structure is included, and heat from the spaced phosphor is transferred into the heat sink structure.

  Another embodiment of an LED-based bulb according to the present invention comprises a pedestal having a plurality of LEDs, the pedestal at least partially including a thermally conductive material. A heat sink structure is included and the pedestal is thermally coupled to the heat sink structure. A phosphor is configured that is spaced from the LED, so that at least some light from the LED passes through the spaced phosphor and is converted to light of a different wavelength. The light bulb emits white light that combines light from the LED and light from the spaced phosphor.

  One embodiment of a light source for a light bulb or lamp according to the present invention comprises a plurality of solid state light emitters and a pedestal having an upper surface. The pedestal also has a plurality of first sides and a plurality of second sides. The first side can be at an angle greater than 90 degrees with respect to the top surface, and the second side can be at an angle less than 90 degrees with respect to the top surface. The solid state light source is attached to at least some of the first side and the second side.

  These and other additional features and advantages of the present invention will be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings.

It is sectional drawing of one Example of a prior art LED lamp. FIG. 6 is a cross-sectional view of another embodiment of a prior art LED lamp. 1 is a side view of an embodiment of a pedestal according to the present invention. It is a perspective view of one Example of the LED lamp by this invention. FIG. 6 is a perspective view of another embodiment of an LED lamp according to the present invention. It is a perspective view of the LED lamp shown in FIG. 5 which shows the light ray from a light source. FIG. 6 is a cross-sectional view of another embodiment of an LED lamp according to the present invention. FIG. 3 is a polar diagram showing a radiation pattern for an embodiment of an LED lamp according to the present invention. FIG. 6 is a perspective view of another embodiment of an LED lamp according to the present invention. FIG. 6 is a side view of another embodiment of a pedestal according to the present invention. It is a perspective view of the pedestal shown in FIG. FIG. 6 is a perspective view of another embodiment of a lamp according to the present invention. FIG. 6 is a perspective view of another embodiment of a pedestal according to the present invention. FIG. 6 is a perspective view of another embodiment of an LED lamp according to the present invention. FIG. 6 is a perspective view of another embodiment of a pedestal according to the present invention.

  The present invention is directed to various embodiments of lamp structures that provide LED chips attached to a thermally conductive pedestal. As a result, the LED lamp can approach a uniform omnidirectional light emission pattern modeled on the light emission pattern of a conventional incandescent lamp bulb. Some LED bulbs according to the present invention are particularly applicable for use as LED lamps for A bulb replacements. Embodiments in accordance with the present invention are constructed from a particular molded pedestal having a surface adapted to mount a solid radiating portion, which can be made from a thermally conductive material or thermally away from the radiating portion. It can have elements that provide conduction. Some examples of pedestals can include multiple LED-based emitters, at least some of which emit in different directions away from the pedestal. When used with spaced phosphors and diffuser domes, the particular angle and emission pattern of the LEDs can give the lamp an omnidirectional emission pattern.

  Some pedestals according to the present invention can be attached to a heat sink structure, so that the heat conducted away from the radiating part can diffuse into the heat sink structure, Can be dissipated to the surroundings. This configuration also allows the pedestal to be easily combined with molded spaced phosphors with good special color uniformity, and the spaced phosphors are also attached to the heat sink. The spaced phosphors can take many different shapes, such as generally spherical, and the pedestal is at least partially constructed within the spherical phosphor. This provides a configuration that provides improved and more pronounced color uniformity due to its radiating portion providing an approximate point light source within the pedestal and spaced phosphors. The light emitted from the pedestal's emitting part passes through the phosphor material at approximately the same angle and passes through approximately the same amount of phosphor. That is, the optical path through which the photons pass from the pedestal emitter through the phosphor is substantially the same, giving the LED bulb a significant emission color uniformity.

  This approximate point source configuration also achieves more uniform emission at different viewing angles, so some of the embodiments can be particularly applied to replacing standard incandescent based light sources. As discussed further below, the spaced phosphor configuration can also be characterized as having a higher photon conversion efficiency for improved thermal management.

  On the pedestal, different solid-state emitters such as LEDs, LED chips, or other LED packages / components (“LED chips”) can be included. In some embodiments, the pedestal can be utilized in a lamp that emits white light, where the lamp is light from one or more phosphors in the phosphor that are spaced apart from light from the LEDs on the pedestal. And emits white light. In some examples, the pedestal can comprise an LED chip that emits blue, and the shaped and spaced phosphor can include a phosphor material that absorbs blue light and emits yellow light. . In operation, part of the blue LED chip light passes through the spaced phosphors and the remaining part is absorbed by the yellow phosphor and re-emitted as yellow or green light, these lamps are blue LED light and phosphor It emits white light combined with light. The lamp according to the invention can also include different LEDs and conversion materials that emit different colors of light, which absorb light and re-emit different colors of light, so that the lamp can be used for color temperature and color rendering, etc. Emits light with the desired properties.

  The lamp according to the invention can have fewer components and can be manufactured more easily and cheaply. For example, by having spaced phosphors, the LED chip on the pedestal can be driven with a higher drive current without the risk of heat from the LED chip degrading the phosphor. Thus, fewer LED chips are required to achieve the desired lamp flux. The pedestal also attaches multiple radiating sections to provide a cost effective method while simultaneously providing a heat path to dissipate heat from the radiating sections.

  Although the invention is described herein with reference to specific embodiments, the invention can be embodied in many different forms and should be construed as limited to the embodiments set forth herein. It is understood that it is not. Specifically, although the present invention is described below with respect to particular lamps or lighting components having different configurations of LEDs, LED chips, or LED components (“LED chips”), the present invention is many different. It is understood that many other lamps having a configuration can be used. The components can have different shapes and dimensions than those shown, and can include a different number of LEDs or LED chips.

  Also, when an element such as a layer, region, or substrate is located "on" another element, this element can be located directly on the other element, or there can be intervening elements It is understood. Furthermore, relative terms such as “inner”, “outer”, “upper”, “above”, “lower”, “beneath”, and “below” are used herein. , As well as similar terms, can be used to describe the relationship of one layer or another region. It is understood that these terms encompass different orientations of the device in addition to the orientation shown in the figures.

  In this specification, the terms first, second, etc. may be used to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers And / or section should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Accordingly, a first element, component, region, layer, or section discussed below may be referred to as a second element, component, region, layer, or section without departing from the teachings of the present invention. .

  In the present specification, embodiments of the present invention will be described with reference to cross-sectional views that are schematic views of embodiments of the present invention. Thus, the actual thickness of the layers can be different and variations from the shape of the figure are expected, for example, as a result of manufacturing techniques and / or tolerances. Embodiments of the present invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. Regions shown or described as square or rectangular typically have round or curved features due to normal manufacturing tolerances. Thus, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the exact shape of the region of the device, nor are they intended to limit the scope of the invention.

  FIG. 3 illustrates one embodiment of an LED pedestal 50 according to the present invention configured to hold an LED chip 52 in an LED lamp or bulb (“LED lamp”), the pedestal 50 and its LED being an LED lamp. Work as a light source for. The pedestal 50 is generally elongated and can have multiple surfaces that can hold multiple LED chips at different angles. In the illustrated embodiment, the pedestal 50 has an upper surface 54 on which the LED chip 52 is attached. When the pedestal 50 is mounted vertically, the top surface is substantially horizontal. The pedestal also includes a plurality of pedestal and emitter surfaces 56, at least a portion of which is also configured to hold the LED chip 52. It will be appreciated that the pedestal 50 can have many shapes and that different numbers and dimensions of the radiating surface 56 can be configured at different angles with respect to the top surface 54. In the illustrated embodiment, there are six radiant surfaces, each radiant surface located on the upper portion of the pedestal, and each having substantially the same dimensions and the same angle. In the illustrated embodiment, these sides are at an angle greater than 90 ° with respect to the top surface 54, and thus the thickness of the pedestal 50 decreases as it goes down from the top surface 54. In some embodiments, the side angle can be about 95 ° or more relative to the top surface, and in other examples, the side angle can be about 100 ° or more relative to the top surface. . In yet another embodiment, the side angle can be about 105 ° or more relative to the top surface. In one embodiment, the side angle is about 105 ° with respect to the top surface.

  LED chips 52 can be included on at least some of the radiating side surfaces 56, and in the illustrated embodiment, LED chips 52 are included on three of the side surfaces 56. Without being limited thereto, Cree, Inc., located in Durham, NC. Many different commercially available LED chips or LED packages can be used, including those commercially available. These LED chips are mounted in place using known methods and materials described below. In this embodiment, an uncovered side surface 56a is included between the side surfaces 56 having the LED chips 52. In other embodiments, some or all of the uncovered side surfaces 56a are provided with LED chips 52. It is understood that there are no uncovered sides between some or all of the LED chips that can be attached. The number of LED chips included on the top and side surfaces depends on the luminous flux of the LED chip 52 and the desired luminous flux and light emission pattern for the LED lamp utilizing the pedestal 50. In different embodiments, the top surface 54 and the side surface 56 may each have no LED chip, or may have more than one LED chip. By having a radiating portion on the top surface 54 and side surface 56, light is emitted from the pedestal up and to the side at a slight downward angle. This combination of illumination directions is adapted to provide omnidirectional lamp radiation when light is dispersed as described below.

  Pedestal 50 also includes base sides 58 below sides 56 and 56a, and in the illustrated embodiment, there are as many base sides 58 as radiant sides 56 and 56a; Construct an extension line. It will be appreciated that in other embodiments, there may be a different number of base sides 58 or the pedestal may take on different shapes, such as a cylindrical shape within this region. In the illustrated embodiment, the base surface has an angle of less than 90 ° with respect to the upper surface 54, so in this region the width of the pedestal increases as it goes down. It will be appreciated that the base side surface 58 can be many different angles with respect to the top surface 54, with a suitable angle being about 70 ° or greater. In some embodiments, this angle can be greater than 90 °. In some embodiments, the base side can also have LED chips, depending on the desired LED lamp flux and emission pattern. In the illustrated embodiment, these sides do not have LED chips.

  The pedestal 50 can also include electrical conductors (not shown) necessary to apply an electrical signal to the LED chip 52. This can include conductive traces, wire bonds, or wires coated with an insulator. The LED chips can be interconnected in different series and parallel configurations, and in some embodiments, the LED chips are interconnected so that all LED chips 52 can emit light with a single electrical signal. The

  The pedestal 50 can at least partially include a thermally conductive material, and many different materials can be used, such as different metals including copper, aluminum, or metal alloys. Different embodiments of the pedestal 50 should be configured to have the necessary features to properly conduct heat away from the LED chip. In some embodiments, the pedestal 50 can have an internal solid section that provides a thermal path, the pedestal being solid for greater than 50%. In yet other embodiments, the pedestal 50 can be solid for greater than 70%, and in other embodiments about 100% can be solid. In embodiments where the pedestal is substantially hollow, a heat dissipating device such as a heat pipe can be included to conduct the heat of the LED chip. The pedestal can be manufactured using many different well-known methods described below, such as die casting or metal stamping.

  The surface of the pedestal 50 should include a reflective layer / surface, particularly in areas not covered by the LED chip 52. In the LED lamp embodiments described below that utilize spaced phosphors, approximately 50% of the phosphor emission travels back toward the pedestal due to isotropic phosphor emission. In other embodiments using a diffusing dome, some of the light passing through the dome may be backscattered towards the pedestal 50. A pedestal 50 whose surface has good reflectivity can reflect at least some of the photons emitted / scattered back to improve the emission efficiency of the lamp, thus contributing to the useful emission of the LED lamp. LED chips and component substrates typically have lower effective reflectivity due to extraction loss and / or low surface reflectivity. Inclusion of a reflective surface not covered by the LED chip increases the emission efficiency of the LED lamp. Reflective layers / surfaces are many, including but not limited to white paint, reflective particles, reflective metals, or reflective multilayer semiconductor structures such as distributed Bragg reflectors (DBR) It is understood that different materials and structures can be included. In some embodiments, these surfaces can be coated with a material having a reflectivity of about 75% or greater for lamp light; in other embodiments, the material is about It can have a reflectance of 85% or more. In yet another embodiment, the material can have a reflectivity of about 95% or greater for lamp light.

  The pedestal 50 can be mounted in many different LED lamps according to the present invention that can have many different features. FIG. 4 shows an LED lamp 70 with a pedestal 72 similar to the pedestal 50 described above. The pedestal 72 is attached to the heat sink structure 74 with good thermal contact between them. An LED chip 76 is attached to the surface of the pedestal 72 and is interconnected using a conductor as described above.

  The heat sink structure 74 can at least partially include a thermally conductive material, and many different thermally conductive materials can be used, such as different metals including copper, aluminum, or metal alloys. The heat sink structure 74 can also include other heat dissipation features such as heat fins 78 that increase the surface area of the heat sink to facilitate more efficient dissipation to the surroundings. A heat sink reflective layer or material may also be included on the surface of the heat sink structure 74 to reflect light as described above with respect to the reflective layer / surface of the pedestal 50. In one embodiment, the top surface 82 of the heat sink structure 74 around the pedestal 72 can include a reflective layer, which can be made from the materials described above, and can be heated using well-known methods. Can be formed on the sink structure 74

  The pedestal 72 can be attached to the heat sink structure 74 using different well-known methods or materials such as thermally conductive bonding material or thermal grease. Conventional thermally conductive grease can contain ceramic materials such as beryllium oxide and aluminum nitride, or metal particles such as colloidal silver. In other embodiments, the pedestal 72 can be attached to the heat sink structure by a thermally conductive device such as a clamping mechanism, screw, or thermal adhesive. These devices and materials can hold the pedestal 72 firmly to the heat sink structure 74 to maximize thermal conductivity. In one embodiment, a thermal grease layer having a thickness of about 100 μm and a thermal conductivity k = 0.2 W / m−k is used. This configuration provides an efficient heat conduction path to conduct heat from the pedestal 72 to the heat sink structure.

  The heat sink structure 74 can also include features for connecting to a power source such as a different electrical receptacle. In some embodiments, the heat sink structure can include features of a type that are compatible with conventional electrical receptacles. For example, the heat sink structure can include features for attachment to a standard screw socket and can include a threaded portion that can be screwed into the screw socket. In other embodiments, the heat sink structure can include a standard plug, and the electrical receptacle can be a standard receptacle, or can include a GU24 type base unit. In other examples, the heat sink structure can include a clip, and the electrical receptacle can be a receptacle that receives and holds the clip (eg, used in many fluorescent lamps). These are just some of the options for the heat sink structure and receptacle, and other configurations can be used.

  In some embodiments, the heat sink structure 74 can include a conductor for applying an electrical signal from the electrical receptacle to the pedestal 72 and then to the LED chip 76. A power unit (not shown) can also be included to adjust or modify the electrical signal from the receptacle before applying it to the pedestal 72. This can include signal conversion (eg, analog to digital conversion, signal rectification, and / or signal amplification or reduction).

  FIG. 5 shows an embodiment of an LED lamp 90 according to the present invention. The LED lamp 90 includes a pedestal 92, a heat sink structure 94, and an LED chip 96 configured similarly to the same features described above shown in FIG. In this embodiment, the LED lamp 90 includes a molded spaced phosphor 98 configured around the pedestal 92 so that at least some light from the LED chip 96 passes through the spaced phosphor. In accordance with the present invention, spaced phosphors 98 can take many different shapes, such as hemispherical, elliptical, conical, and can be many different dimensions. In some embodiments, the spaced phosphors may not cover the entire pedestal 92. In the illustrated embodiment, the spaced phosphors 98 are in the form of spheres attached to a heat sink structure 94, and the pedestal 92 and its LED chip 96 are at least partially configured within the spherical phosphor 98. The The lamp 90 also includes a threaded portion 95 for attaching the lamp 90 to the screw socket.

Many different phosphors can be used within the shaped phosphor 98, and the present invention is particularly adapted (phosphor layers, or mixed) to lamps that emit white light. As mentioned above, in some embodiments according to the present invention, the LED chip 96 can emit light in the blue wavelength spectrum, and the shaped phosphor 98 absorbs at least a portion of the blue light. Yellow (or green) can be re-released. Thus, the lamp can emit white light that is a combination of blue light and yellow light. In some examples, blue LED light can be converted by a yellow conversion material using a commercially available YAG: Ce phosphor, but (Gd) such as Y ₃ Al ₅ O ₁₂ : Ce (YAG) , Y) ₃ (Al, Ga) ₅ O ₁₂ : Using conversion particles made from phosphors based on the Ce system, a wide range of yellow spectral emission is possible. Not limited to that,
_{Tb 3-x RE x O 12} : Ce (TAG), RE = Y, Gd, La, Lu, or _{Sr 2-x-y Ba x} Ca y SiO 4: Eu
Other yellow phosphors can also be used to produce white light when used with LED-based emitters that emit blue light.

The molded phosphor 98 can include a second phosphor material, and the second phosphor material can be mixed within the molded spaced phosphor 98 or on the molded phosphor. Can be included as a second layer. In some embodiments, each of the two phosphors can absorb LED light and re-emit different colors of light. In these examples, the colors from the two phosphor layers can be combined to yield a higher CRI white than the white hue is different (warm white). This can include light from the yellow phosphor described above, and this light can be combined with light from the red phosphor. Different red phosphors can be used,
Sr _x Ca _1-x S: Eu, Y, Y = halogen compound,
CaSiAlN ₃ : Eu, or Sr _2-y Ca _y SiO ₄ : Eu
Is included.

Other phosphors can also be used to provide color emission by converting substantially all light into a particular color. For example, the following phosphors can be used to generate green light.
SrGa ₂ S ₄ : Eu,
_{Sr 2-y Ba y SiO 4} : Eu, or _{SrSi 2 O 2 N 2: Eu} .

The following lists some additional suitable phosphors, although other phosphors can be used. Each exhibits excitation in the blue and / or UV emission spectrum, provides the desired peak emission, has efficient light conversion, and has an acceptable Stokes shift.
Yellow / green (Sr, Ca, Ba) (Al, Ga) ₂ S ₄ : Eu ²⁺
Ba ₂ (Mg, Zn) Si ₂ O ₇ : Eu ²⁺
Gd _0.46 Sr _0.31 Al _1.23 O _x F _1.38 : Eu ²⁺ _0.06
(Ba _1-xy Sr _x Ca _y ) SiO ₄ : Eu
Ba ₂ SiO ₄ : Eu ²⁺
Red Lu ₂ O ₃ : Eu ³⁺
_{(Sr 2-x La x)} (Ce 1-x Eu x) O 4
Sr ₂ Ce _1-x Eu _x O ₄
Sr _2-x Eu _x CeO ₄
SrTiO ₃ : Pr ³⁺ , Ga ³⁺
CaAlSiN ₃ : Eu ²⁺
Sr ₂ Si ₅ N ₈ : Eu ²⁺

  Different sized phosphor particles can be used, including but not limited to particles in the range of 10 nanometers (nm) to 30 micrometers (μm) or larger. Smaller particle sizes typically scatter and mix colors better than larger sized particles to provide more uniform light. Larger particles usually emit light that is more efficient in converting light but less uniform when compared to smaller particles.

  In some embodiments, a spherical transmissive material can be provided and the phosphor can be deposited on the inner layer or the outer layer, or both. To form this layer, a phosphor can be provided in the adhesive, and the phosphor can also have different concentrations or amounts of phosphor material in the adhesive. Typical concentrations are in the range of 30-70% by weight. In one embodiment, the phosphor concentration is about 65% by weight and is preferably uniformly distributed throughout the spaced phosphors. The shaped phosphor 98 can also have different regions with different conversion materials and different concentrations of conversion material.

  Different materials can be used for the adhesive, and these materials are preferably robust after curing and substantially transparent in the visible wavelength spectrum. Suitable materials include silicones, epoxies, glasses, inorganic glasses, dielectrics, BCB, polyimides, polymers, and hybrids thereof, with preferred materials being their high transmission and reliability in high power LEDs. Therefore, it is silicone. Suitable phenyl and methyl-based silicones are commercially available from Dow® Chemical. The adhesive can be cured using many different curing methods depending on different factors such as the type of adhesive used. Different curing methods include, but are not limited to, thermal, ultraviolet (UV), infrared (IR), or air curing.

  The phosphor layer can be added using different processes, including but not limited to spin coating, sputtering, printing, powder coating. As noted above, the phosphor layer can be added with the adhesive material, but it is understood that the adhesive is not essential. In still other embodiments, the phosphor layer can be manufactured separately and then attached to a transmissive sphere.

  Shaped spaced phosphor 98 can also include improved thermal management features to reduce the heat of phosphor conversion. During operation, the phosphor may simply generate heat from the light conversion process. Within a remote phosphor configuration, if the remote phosphor has a thermally conductive path that is insufficient to dissipate the phosphor conversion heat, this heat may accumulate to an unacceptable level. Without an effective heat dissipation path, thermally isolated remote phosphors can have higher operating temperatures, which can lead to phosphor degradation, conversion inefficiencies, and color changes. There is.

  In some embodiments, the molded spaced phosphor 98 can include a transmissive material that is a thermally conductive material and is in the form of a desired spaced phosphor shape. In the illustrated embodiment, the spaced phosphors are spherical, but can have many other shapes as described above. The phosphor can be included as a layer on the spherical transmissive material or can be mixed with the spherical material. During operation of the LED lamp 90, the phosphor conversion heat is concentrated in the phosphor material. The thermal conductivity of the carrier sphere helps to diffuse this heat laterally toward the edge of the sphere in contact with the heat sink structure 94 in the illustrated embodiment. The sphere is preferably attached to the heat sink structure by a conductive material such as a thermal grease layer, and heat can flow from the sphere into the heat sink structure and efficiently dissipate to the surroundings in the heat sink structure. .

  The shaped transmissive material can include different materials such as glass, quartz, silicon carbide (SiC), sapphire. The molded permeable material can also have different thicknesses, and a suitable thickness range is 0.1 mm to 10 mm or greater. It will be appreciated that other thicknesses may be used depending on the properties of the material for the carrier layer. The material should be thick enough to provide sufficient lateral heat diffusion for specific operating conditions. In general, the higher the thermal conductivity of the material, the thinner the material can be to provide the necessary heat dissipation. These materials can efficiently spread heat laterally, so that the large area required by materials with lower thermal conductivity is not required. Different factors, including but not limited to cost and transparency to source light, can affect which material is used.

  In addition to the conversion efficiency of the pedestal 92 and molded phosphor 98 configurations discussed above, this configuration can also provide conversion uniformity. Referring now to FIG. 6, an LED lamp 100 similar to the LED lamp 90 is shown and the same reference numerals have been used for similar features. The LED chips 96 are collected on top of the pedestal 92 and are located in the molded phosphor 98, preferably at or near the center of the molded phosphor. With this configuration, the LED chip 96 can approximate a point source within the shaped phosphor 98 so that the light beam 102 strikes the shaped phosphor 98 at approximately the same angle and is spaced apart from the phosphor (eg, Proceed through the same optical path length in the coated sphere). Assuming that the shaped phosphors have approximately the same thickness throughout, the light rays undergo a similar amount of phosphor material and a similar level of light conversion. This allows color uniformity to emitted light to be maintained when the spaced phosphors have a phosphor coating with spatial consistency.

It will be appreciated that spaced phosphors and pedestals can be constructed in many different ways according to the present invention. In some embodiments, the spaced phosphor can include scattering particles in a layer on the shaped spaced phosphor, can be mixed with the phosphor material, or can be transparent heat. It can be mixed with a conductive material. Scattered particles are not limited to that,
silica gel,
Zinc oxide (ZnO),
Yttrium oxide (Y ₂ O ₃ ),
Titanium dioxide (TiO ₂ ),
Barium sulfate (BaSO ₄ ),
Alumina (Al ₂ O ₃ ),
Fused quartz (SiO ₂ ),
Fumed silica (SiO ₂ ),
Aluminum nitride,
Glass beads,
Zirconium dioxide (ZrO ₂ ),
Silicon carbide (SiC),
Tantalum oxide (TaO ₅ ),
Silicon nitride (Si ₃ N ₄ ),
Niobium oxide (Nb ₂ O ₅ ),
Boron nitride (BN) or phosphor particles (for example, YAG: Ce, BOSE)
Many different materials can be included. In various combinations of materials or combinations of different forms of the same material, more than one scattering material can be used to achieve a particular scattering effect. Shaped spaced phosphors or diffuser domes can also include surface roughening or shaping to facilitate light extraction.

  FIG. 7 shows an embodiment of an LED lamp 120 according to the present invention. The LED lamp 120 is similar to the LED lamp 90 shown in FIG. 5, and includes a pedestal 122 with an LED chip 124 attached to the top and side surfaces of the pedestal. The pedestal 122 is attached to the heat sink structure 126, and the molded spaced phosphor 128 is also attached to the heat sink structure 126 over the pedestal 122. The lamp 120 also includes a shaped diffuser dome 130, which is also attached to the heat sink structure 126, but it will be appreciated that it can be mounted within the lamp 120 in many different ways. The diffusion dome 130 can include diffusing or scattering particles as described above. The scattering particles can be provided in a curable adhesive formed in a generally dome shape. In some embodiments, white scattering particles can be used, and the dome has a white color, thereby hiding the color of the phosphor in the shaped and spaced phosphor to give the LED lamp a generally white appearance. give. The diffuser dome is configured to diffuse or scatter light from spaced phosphors so that the LED lamp emits a desired pattern of light, such as omnidirectional light. The lamp 120 also includes a threaded portion 132 for attaching the lamp 120 to the screw socket.

  The diffuser dome can have many different shapes and can be configured in many different ways within the lamp according to the invention. In some embodiments, the diffuser dome and the phosphor material can include a single component. In some examples, the phosphor can include a layer on the diffuser, and the phosphor or diffuser material can be mixed. If the lamp has an LED chip that emits a blue color, a diffuser dome with phosphor material and neutral scattering particles can be used, so the lamp combines light from the phosphor and light from the LED chip. Emits white light.

  As described above, the LED lamp according to the present invention can be configured to provide an omnidirectional emission pattern, and emission variation at different emission angles is limited. FIG. 8 is a polar diagram 140 showing the relative luminous intensity distribution in the far field in angular space for an embodiment of an LED lamp according to the present invention. In the polar diagram 140, θ is an inclination angle from the z axis shown in FIG. 3, and φ is an azimuth angle from the x axis. The number 142 around the circle refers to the tilt angle θ, and 0 ° is directly above the top surface of the pedestal. The distribution from 0 ° to 180 ° is symmetric with respect to the distribution from 360 ° to 180 °. In the polar diagram, the azimuth angle φ is represented as a plurality of slices, and these slices form a continuous band. The width of the band at a particular angle θ reflects how much intensity variation exists across the 360 ° azimuth at this angle θ. The azimuth average line 144 represents the azimuth average intensity at each angle θ. By using the pedestal, the spaced phosphor, and the diffusion sphere according to the present invention, the variation in φ can be substantially eliminated. In the illustrated embodiment, for θ from 0 ° to 150 °, the average (relative) intensity of φ varies within the range of 0.920 to 0.696. This corresponds to an intensity variation of ± 13.8% around an average value of 0.808. It is understood that other embodiments according to the present invention can provide different intensity variations both above and below this 13.8%.

  In some lamp embodiments, a larger shaped and spaced phosphor provides a higher ratio of high reflectivity surface area to LED chip / component surface area, ie higher cavity reflectivity and efficiency. be able to. Larger spaced phosphors can also reduce conversion density and associated heat. That is, larger spaced phosphors with larger areas tend to reduce the incoming photon flux density per unit phosphor area. Also, the larger spaced phosphors can make the thermal management of the heat generated by the phosphors easier, thus maintaining the phosphor operating temperature near ambient temperature and the efficiency and lifetime of the phosphor. Can be improved. However, these larger phosphors can result in higher material costs for larger spaced phosphors and lamp containers.

  It will be appreciated that many different pedestals can be used in different embodiments according to the invention. FIG. 9 illustrates another embodiment of an LED lamp 160 according to the present invention, which includes a pedestal 162 attached to a heat sink 164. In this example, the pedestal is generally triangular and has a top surface 166 and three side surfaces 168. An LED chip 170 is attached to each of the surfaces 166, 168, and an electrical connection (not shown) between the LED chips causes the LED chips to emit light in response to electrical signals. The LED lamp 160 can also comprise the shaped spaced phosphor or diffuser dome described above.

  10 and 11 illustrate another embodiment of a pedestal 180 according to the present invention, which has a top surface 182, three radiating side surfaces 184, and three open side surfaces 186. FIG. One LED chip 188 is mounted on the top surface 182 and one LED chip is mounted on each emitter side 184, and the pedestal has a total of four LED chips. Similar to the embodiment described above, the LED chip 188 comprises an electrical connection, and thus the LED chip 188 emits light in response to an electrical signal. Within the pedestal 180, the radiating portion side 184 has an angle greater than 90 ° with respect to the top surface 182, and in one embodiment has an angle of about 105 ° with respect to the top surface. It will be appreciated that the radiant surface 184 may be at many different angles with respect to the top surface 182. In this example, the open side 186 has an angle of less than 90 ° with respect to the top surface relative to the top surface 182.

  FIG. 12 shows another embodiment of the LED lamp 190 according to the present invention, which uses the pedestal 180 shown in FIGS. The pedestal 180 is attached to the heat sink structure 192, and the molded spaced phosphor 194 is made from the same material as the molded spaced phosphor described above. The molded spaced phosphor is also attached to the heat sink structure 192 and the pedestal 180 is configured within the spaced phosphor 194. This embodiment can also include a diffuser dome to further scatter or diffuse light into an omnidirectional pattern.

  FIG. 13 shows yet another embodiment of a pedestal 210 according to the present invention, which has a top surface 212 and four radiating side surfaces 214. Above each of these surfaces is an LED chip 216 that is interconnected to emit light in response to electrical signals, as described above. In this embodiment, each of the radiating portion side surfaces 214 has an angle of less than 90 degrees with respect to the top surface 212. In this example, the side surface 214 is at an angle of about 80 ° with respect to the top surface 212, but the side surface 214 is not limited to that with respect to the top surface 212, but is particularly limited to about 90 °, 100 °, 105 It will be appreciated that many other angles can be included, including °. Other pedestals according to the invention can have different numbers of surfaces at different angles and orientations to obtain the desired release pattern. In the illustrated embodiment, the pedestal 210 includes a substantially solid thermally conductive material, but other embodiments can include a hollow pedestal or other heat dissipating heat, such as a heat pipe. It is understood that it can have features. The pedestal 210 can be utilized in different LED lamps according to the present invention, including those having the heat sink structure described above, molded spaced phosphors, and a diffuser dome.

  FIG. 14 illustrates one embodiment of an LED lamp 230 according to the present invention, which utilizes a pedestal 210 similar to that shown in FIG. 13 and its LED chip 216. The lamp 230 includes a heat sink structure 232 and a container 234 that can be the molded spaced phosphor or diffuser dome described above. The LED lamp 230 further includes a threaded portion 236 for attaching to a screw socket. In this embodiment, the pedestal 210 is mounted in the container 234 by a heat pipe 238 that conducts heat from the pedestal 210 and conducts the heat to the heat sink structure 232 and heat heat. In the sink structure 232, heat can be dissipated more efficiently to the surroundings. It will be appreciated that other heat conducting elements may be used in embodiments according to the present invention.

  It will also be appreciated that many different pedestals can be constructed on the heat pipe shown in FIG. FIG. 15 shows another embodiment of a pedestal 250, which has an upper surface 252 and five radiating side surfaces 254, each of which has an LED chip 256, the LED chip 256 as described above. It can be electrically connected to other LED chips. In this example, the radiant side 254 has an angle less than 90 ° with respect to the upper surface 252, but in other examples, some or all of the radiant side 254 is more than 90 ° with respect to the upper surface 252. Can have a large angle. The pedestal is attached to a heat pipe 258 that conducts heat from the pedestal, and thus heat can be dissipated to the environment, such as through the heat sink structure described above.

  The lamp according to the invention can be configured in many different ways other than the embodiments described above. In some embodiments, the LED chip attached to the pedestal can be a white emitter, such as a warm white emitter. In some of these embodiments, molded spaced phosphors may not be required to convert light from the LED chip. The diffuser dome can include neutral scattering elements to diffuse the LED chip light in a desired emission pattern. However, it is understood that shaped and spaced phosphors can also be used in embodiments having a white emitter on the pedestal to further modify the emitter light. In yet other embodiments, the pedestal can include a white emitter and a different colored emitter, and in different embodiments of these lamps, spaced phosphors and diffusers are used to achieve the desired lamp emission. Can be obtained.

  The pedestal according to the invention can be manufactured using different methods. As mentioned above, the pedestal can be stamped from sheet metal and then bent into a pedestal shape. Although this manufacturing method is cost effective, the resulting pedestal is hollow and may not have the necessary capacity to conduct heat from the radiant section without the use of additional devices such as heat pipes. is there. However, it is understood that a stamped pedestal with additional thermal management features can be provided to provide the desired heat dissipation.

  Alternatively, pedestals can be die-casted, which requires initial equipment costs, but in large quantities following the equipment, large quantities of these pedestals are relatively cost effective. An aluminum material can be used for the pedestal using the die casting method, and the pedestal can be die-cast so that the recess is at the position where the LED chip is to be mounted. The recessed area should be the same shape as the mounting area of the LED chip and slightly larger than that, and the depth of the recessed area should hold the LED chip so that the LED chip does not easily fall out of the recessed area. is there. The surface of the pedestal can then be electroplated with a thin Ni / Cu or Ni / Ag layer to allow reflowability. A dry film can then be applied into the surface of the recessed area and the entire pedestal can be coated with a reflective coating such as white paint, reflective particles, reflective metal, DBR. The dry film can then be removed from the recessed areas to expose the Cu or Ag surfaces in the recessed areas, and then solder paste can be applied to these surfaces. Next, the LED chip can be disposed in the recess by a pick-and-place method or the like. In some examples, the LED chip can have an electrically isolated back metallized surface. The surface tension of the recess and solder paste can hold the LED chip in place before reflow. If the surface is tilted, the pedestal can be oriented so that gravity helps hold the LED chip in the recess. In the case of a pedestal having a surface greater than 90 ° with respect to the top surface, the pedestal should be held upside down to hold the LED chip within the side recess. The pedestal can then be reflowed and the pedestal with the LED chip on the top surface may need to be reflowed again. Front wiring can be included to interconnect the LED chips.

  It will be appreciated that different manufacturing methods according to the present invention may have more or fewer steps than those described above and may have different steps when utilizing different components. For example, for surface mounted LEDs on a metal core printed circuit board, different methods can be used to attach to the pedestal. Grooves can be cut into the metal core PCB, whereby the metal core PCB can be bent and therefore wrapped around the pedestal. Eutectic solder can be used to join the metal core PCB to the pedestal.

  Although the present invention has been described in detail with reference to certain preferred configurations of the invention, other forms are possible. Accordingly, the spirit and scope of the present invention should not be limited to the forms described above.

Claims (38)

A light emitting diode (LED) based light bulb,
An elongated pedestal having a plurality of surfaces;
A plurality of LEDs, each of said LEDs being attachable to one of said surfaces, comprising a thermally conductive path for conducting heat away from said LED, said pedestal;
A light bulb comprising a diffuser configured for the LED, wherein the light from the LED passes through the diffuser and modifies the emission pattern of the LED to produce a desired light bulb emission pattern. .   The light bulb of claim 1, wherein the diffuser modifies the emission pattern of the LED to an omnidirectional pattern.   The bulb of claim 1, wherein the diffuser comprises a diffuser dome.   The molded phosphor further spaced apart with respect to the LED, wherein at least some light from the LED passes through the spaced phosphor and is converted to light of a different wavelength. The light bulb according to 1.   The light bulb of claim 1, further comprising a heat sink structure, wherein the thermally conductive path is thermally coupled to the heat sink structure.   The light bulb of claim 5, further comprising a spaced phosphor attached to the heat sink structure, wherein heat from the spaced phosphor is conducted to the heat sink structure.   The light bulb of claim 1, wherein the pedestal comprises at least a portion of a thermally conductive material.   The pedestal has a top surface and a plurality of side surfaces having an angle greater than 90 degrees with respect to the top surface, at least some of the side surfaces having one of the LEDs. light bulb.   The bulb of claim 1, wherein the pedestal has a top surface and a plurality of side surfaces having an angle greater than about 105 degrees with respect to the top surface.   The light bulb of claim 4, wherein the LED is configured for the spaced phosphors such that light rays emanating from the LEDs in different directions pass through the same thickness of the spaced phosphors.   The light bulb of claim 4, wherein the LED approximates a point light source within the spaced phosphor.   The bulb of claim 2 having an omnidirectional emission pattern with an intensity variation of about +20 percent or less.   The bulb of claim 2 having an omnidirectional emission pattern with an intensity variation of about +15 percent or less. A pedestal having a plurality of solid state light sources, wherein the pedestal comprises at least part of a thermally conductive material;
A heat sink structure in which the pedestal is thermally coupled, wherein heat from the solid state light source is transferred through the pedestal into the heat sink structure;
A solid state lamp comprising: a spaced phosphor that is thermally coupled to the heat sink structure, wherein heat from the spaced phosphor is transferred into the heat sink structure.   The lamp of claim 14, further comprising a diffuser configured to disperse light from the spaced phosphors and the solid state light source in an omnidirectional pattern.   15. The lamp of claim 14, wherein the spaced phosphor is configured such that at least some light from the solid state light source passes through the spaced phosphor and is converted to light of a different wavelength.   15. The pedestal has an upper surface and a plurality of side surfaces having an angle greater than 90 degrees with respect to the upper surface, at least some of the side surfaces having one of the solid state light sources. Lamp.   15. The lamp of claim 14, wherein the solid state light source is configured for the spaced phosphors such that light rays emanating from the solid light source in different directions pass through substantially the same thickness of the spaced phosphors. .   The lamp of claim 14, wherein the solid state light source approximates a point light source within the spaced phosphor.   The lamp of claim 15, wherein the omnidirectional emission pattern has an intensity variation of about +20 percent or less.   The lamp of claim 14, wherein the pedestal further comprises a heat pipe. A light emitting diode (LED) based light bulb,
A pedestal having a plurality of LEDs, the pedestal comprising at least part of a thermally conductive material;
A heat sink structure in which the pedestal is thermally coupled;
A spaced phosphor disposed with respect to the LED, wherein at least some of the light from the LED passes through the spaced phosphor and is converted to light of a different wavelength. A light bulb that emits white light that combines light from the LED and light from the spaced phosphors.   23. The light bulb of claim 22, further comprising a thread portion for attaching the light bulb to a screw socket.   The light bulb according to claim 22, comprising an A light bulb replacement.   The light bulb of claim 22 further comprising a diffuser dome.   23. The light bulb of claim 22, wherein the LED emits blue light and the spaced phosphor comprises a phosphor material that absorbs blue light and re-emits yellow or green light. A light bulb or lamp light source,
A plurality of solid state light emitters;
A pedestal having a top surface, a plurality of first side surfaces, and a plurality of second side surfaces, wherein the first side surface is at an angle greater than 90 degrees with respect to the top surface, and the second side surface is the top surface A light bulb or lamp light source at an angle of less than 90 degrees with respect to and wherein the solid state light emitter is attached to at least some of the first side and the second side.   28. The bulb or lamp light source of claim 27, wherein the solid state light emitter comprises a light emitting diode (LED).   28. The bulb or lamp light source of claim 27, wherein at least one of the solid state light emitters is attached to the top surface.   28. The bulb or lamp light source of claim 27, wherein the pedestal is made from a thermally conductive material.   28. The bulb or lamp light source of claim 27, wherein the solid state light emitters are electrically coupled in series.   28. The bulb or lamp light source of claim 27, wherein the first side is adjacent to the top surface and the second side is adjacent to the first side.   33. The bulb or lamp light source of claim 32, wherein the solid state light emitter is attached to at least some of the first side surfaces.   33. The bulb or lamp light source of claim 32, wherein every other solid state light emitter is attached to the first side.   28. The bulb or lamp light source of claim 27, comprising alternating first and second sides.   28. The bulb or lamp light source of claim 27, wherein the first side and the second side are alternating adjacent to the top surface.   37. The bulb or lamp light source of claim 36, wherein the solid state light emitter is attached to at least some of the first side surfaces.   28. The bulb or lamp light source of claim 27, wherein the top surface is substantially horizontal when the pedestal is vertical.

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